AP3845CP

Data Sheet CURRENT MODE PWM CONTROLLER General Description The AP3842C/3C/4C/5C are high performance fixed frequency current-mode PWM controller series. These integrated circuits are optimized for off-line and DC-DC converter applications with minimum external components. They feature under-voltage lockout (UVLO) circuit with low start-up current, trimmed oscillator for precise duty cycle control, current sense comparator providing maximum current limiting and a totem pole output stage for increasing output current. In addition, these ICs also feature accurate protection against over-temperature, over-current and maximal output power. The AP3842C and AP3844C have UVLO thresholds of 16V(on) and 10V(off); The corresponding thresholds for AP3843C and AP3845C are 8.4 V(on) and 7.6V(off). The AP3842C and AP3843C can operate approaching 100% duty cycle; AP3844C and AP3845C can operate from zero to 50% duty cycle. These ICs are available in SOIC-8 and DIP-8 packages. AP384XC Features · · · · · · · · Low Start-up Current: 50µA Robust VREF Line/Load Regulation Low Line Regulation : 4mV Low Load Regulation : 4mV High Stability of Reference Voltage over a Full Temperature Range: 0.2mV/ oC Operating Frequency up to 500KHz High PWM Frequency Stability over a Full Temperature Range: 2.5% High PWM Frequency Stability under a Full Supply Voltage Range: 0.2% Accurate Over-temperature Protection with Hysteresis UVLO with Hysteresis Applications · · · · · · Off-line Converter DC-DC Converter Voltage Adapter CRT Monitor Power Supply Desktop Power Supply DVD/STB Power Supply SOIC-8 DIP-8 Figure 1. Package Types of AP3842C/3C/4C/5C Sep. 2006 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 1 Data Sheet CURRENT MODE PWM CONTROLLER Pin Configuration AP384XC P/M Package (DIP-8/SOIC-8) COMP VFB ISENSE RT/CT 1 2 3 4 8 7 6 5 VREF VCC OUTPUT GND Figure 2. Pin Configuration of AP3842C/3C/4C/5C (Top View) Pin Description Pin Number 1 2 3 4 Pin Name COMP VFB ISENSE RT/CT Function This pin is the Error Amplifier output and is made available for loop compensation. The inverting input of the Error Amplifier. It is normally connected to the switching power supply output through a resistor divider. A voltage proportional to inductor current is connected to this input. The PWM uses this information to terminate the output switch conduction. The Oscillator frequency and maximum output duty cycle are programmed by connecting resistor RT to VREF and capacitor CT to ground. Operation to 500 kHz is possible. The combined control circuitry and power ground. This output directly drives the gate of a power MOSFET. Peak currents up to 1.0 A are sourced and sunk by this pin. The positive supply of the control IC. This is the reference output. It provides charging current for capacitor CT through resistor RT. 5 6 7 8 GND OUTPUT VCC VREF Sep. 2006 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 2 Data Sheet CURRENT MODE PWM CONTROLLER Functional Block Diagram AP384XC VCC GND 7 34V 5 UVLO S/R 5V REF 8 VREF 2.50V INTERNAL BIAS VREF GOOD LOGIC RT/CT 4 OSC T 6 OUTPUT OVER TEMP PROTECT ERROR AMP (Note) 2R S R R 1V CURRENT SENSE COMPARATOR PWN LATCH Note: Toggle flip-flop used for 3844C/45C only VFB COMP ISENSE 2 1 3 Figure 3. Functional Block Diagram of AP3842C/3C/4C/5C Sep. 2006 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 3 Data Sheet CURRENT MODE PWM CONTROLLER Ordering Information AP384XC Circuit Type Package M: SOIC-8 P: DIP-8 E1: Lead Free Blank: Tin Lead TR: Tape and Reel Blank: Tube AP384XC Package Temperature Range -40 to 85oC Part Number Tin Lead AP3842/3/4/5CM AP3842/3/4/5CMTR Lead Free AP3842/3/4/5CM-E1 AP3842/3/4/5CMTR-E1 AP3842/3/4/5CP-E1 Tin Lead 3842/3/4/5CM 3842/3/4/5CM Marking ID Lead Free 3842/3/4/5CM-E1 3842/3/4/5CM-E1 AP3842/3/4/5CP-E1 Packing Type Tube Tape & Reel Tube SOIC-8 DIP-8 -40 to 85oC AP3842/3/4/5CP AP3842/3/4/5CP BCD Semiconductor's Pb-free products, as designated with "E1" suffix in the part number, are RoHS compliant. Sep. 2006 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 4 Data Sheet CURRENT MODE PWM CONTROLLER Absolute Maximum Ratings (Note 1, 2) Parameter Supply Voltage Output Current Analog Inputs Error Amp Output Sink Current Power Dissipation at TA< 25 oC (DIP-8) Power Dissipation at TA